This invention relates to rock crushing equipment which produces aggregate for use during the construction of roadways. More specifically, the invention relates to a self-propelled rock crusher for producing aggregate suitable for the subbase of a roadway where the rock to be crushed can be blasted rock, boulders and cobbles normally found within the right-of-way of the road being constructed. The aggregate is deposited along the length of the roadway as construction progresses.
During the construction of roads and highways, large volumes of aggregate having specific gradation and compaction specifications are required for producing a firm, stable and moisture resistant load bearing road bed. The road bed in most cases comprises a subgrade, a subbase and a base layer over which a bituminous surface is spread.
Aggregate meeting the specifications for roadway construction is usually produced by crushing rock material in a stationary crushing machine that is permanently located at a remote site where a large volume of such suitable rock material is in existence. A site having such suitable material is usually remotely located from the site of the roadway under construction, thereby requiring that the aggregate be loaded on to trucks and transported to the roadway construction site as required.
The present invention reduces the cost, transportation and timing or scheduling of rock deliveries to the roadway site during the initial stages of roadway construction by providing a self-propelled rock crushing machine capable of producing aggregate on site which meets the specifications for the initial subgrade layer of the roadbed from native material found within the roadway right-of-way. The self-propelled rock crusher can readily travel along the length of the roadway to scoop-up and crush rock material which has been loosened and collected into windrows by earth moving equipment such as graders or the like. The rock crusher then deposits the crushed material on the surface of the roadway for subsequent spreading and compaction.
A tractor unit tows a rock crushing apparatus mounted on a separate frame. The tractor unit is conventionally pivotally mounted to the frame so as to provide mobility for the frame. The tractor unit has positioned within reach of the operator an electrical control panel through which the crushing apparatus can be remotely operated and regulated. Hydraulic controls permit the operator to raise or lower the forward end of the frame to control the position of an inlet portion of the crushing apparatus relative to the ground surface of the roadway.
The crushing apparatus is operated by a number of electrical motors which receive electrical power from a diesel generator mounted on the rear frame. The electrical motors drive several rock moving conveyors to transport material to be crushed from the surface of the roadbed to a first coarse rock crusher then to a second fine rock crusher for deposition to the ground. Also mounted on the frame, in proximity to the diesel generator, are separate compartments containing transformers, breakers and relays as would normally be associated with an electric drive system.
In summary, the mobile rock crusher of the present invention for crushing raw rock material which has been windrowed on a roadway in the translation path of the crusher includes a rigid supporting structure, which includes a frame, and translation means for allowing translation of the frame over the roadway. A selectively actuable scoop is pivotally mounted to the frame for selectively actuable lowering over the roadway into sliding engagement with, so as to collect, the windrowed raw rock material onto the scoop. A first conveyor is mounted to the frame. An upstream loading end of the first conveyor cooperates with the scoop for conveying the raw rock material from the scoop onto a first screen at a downstream depositing end of the first conveyor. The first screen is for screening larger diameter material from smaller diameter material in the raw rock material so that the smaller diameter material falls through the first screen. The larger diameter material translates over the first screen so as to fall into a first crusher mounted to the frame beneath the first screen. A second conveyor mounted to the frame beneath the first crusher is for conveying crushed material from the first crusher into a second crusher mounted to the frame for crushing the crushed material for deposition from the second crusher onto the roadway. The first conveyor may be pivotally mounted to the frame and selectively actuable so as to pivot the scoop and first conveyor into engagement with the roadway.
In one embodiment, a second screen is mounted to the frame and beneath the first crusher for screening fines from crush resulting from the larger diameter material being crushed in the first crusher. The second screen may be inclined so that the crush slides from the second screen onto the second conveyor.
In another embodiment, a third screen is mounted to the frame and beneath a downstream depositing end of the second conveyor. The third screen is for screening further fines from the crush. The third screen may be inclined so that the crush slides from the third screen into the second crusher. A first conduit may be mounted beneath the first screen for directing the smaller diameter material out from a flow path of the larger diameter material passing into the first crusher so that the smaller diameter material falls to the roadway. Second and third conduits may be mounted beneath the second and third screens respectively for directing the fines and the further fines respectively out of a flow path of the crush so as to fall to the roadway.
A hopper may be mounted at the depositing end of the first conveyor, the hopper for directing the raw rock material for deposit onto the first screen. A hopper conveyor may also be mounted under the depositing end of the first conveyor so that the first screen is fed by the hopper conveyor. The hopper conveyor may translate the raw rock material in a forward direction relative to the forward end of the frame. A first guide may be mounted beneath the depositing end of the first conveyor and in inclined opposed relation to the first screen so as to channel the raw rock material into the first crusher. Second and third guides may be mounted in inclined opposed relation to the second and third screens respectively for channelling the crush along the flow path of the crush.
In one embodiment the first crusher may be a jaw crusher the second crusher may be a roll crusher. In one preferred embodiment the first crusher is aft of the second crusher relative to a forward end of the frame, and the second conveyor transports the crush in a forward direction. In another preferred embodiment the first crusher is forward of the second crusher relative to the forward end of the frame, and the second conveyor transports the crush in a rearward direction.
The rock crusher of the present invention may also include material urging means cooperating with the scoop for urging the raw rock material onto the scoop and the first conveyor. The material urging means may be an actuable broom roller, rotatably mounted above the scoop.
The rock crusher of the present invention may further include a tractor means mounted to the forward end of the frame. The tractor means may be a self-powered two wheel tractor pivotally mounted to the forward end of the frame. The translation means may be at least one pair of rear wheels mounted on the frame.
Both the screen and the crushers may be hopper-fed from hoppers mounted to catch and channel material moving along the processing path.